streamline PandasIndexingAdapter indexing logic

Grouping the logic into one method will make it easier overriding the behavior in subclasses (interval index) without affecting much readability. Also it yield more DRY code.
pydata · dcherian · Jul 7, 2025 · May 9, 2025 · May 9, 2025 · May 9, 2025
commit 17ff7e9465ccc627bad2cf08e841deacf41f68e4
diff --git a/xarray/core/indexing.py b/xarray/core/indexing.py
@@ -1838,57 +1838,42 @@ def _convert_scalar(self, item) -> np.ndarray:
         # a NumPy array.
         return to_0d_array(item)
 
-    def _prepare_key(self, key: Any | tuple[Any, ...]) -> tuple[Any, ...]:
-        if isinstance(key, tuple) and len(key) == 1:
+    def _index_get(
+        self, indexer: ExplicitIndexer, func_name: str
+    ) -> PandasIndexingAdapter | np.ndarray:
+        key = indexer.tuple
+
+        if len(key) == 1:
             # unpack key so it can index a pandas.Index object (pandas.Index
             # objects don't like tuples)
             (key,) = key
 
-        return key
+        # if multidimensional key, convert the index to numpy array and index the latter
+        if getattr(key, "ndim", 0) > 1:
+            indexable = NumpyIndexingAdapter(np.asarray(self))
+            return getattr(indexable, func_name)(indexer)
+
+        # otherwise index the pandas index then re-wrap or convert the result
+        result = self.array[key]
 
-    def _handle_result(self, result: Any) -> PandasIndexingAdapter | np.ndarray:
         if isinstance(result, pd.Index):
             return type(self)(result, dtype=self.dtype)
         else:
             return self._convert_scalar(result)
 
     def _oindex_get(self, indexer: OuterIndexer) -> PandasIndexingAdapter | np.ndarray:
-        key = self._prepare_key(indexer.tuple)
-
-        if getattr(key, "ndim", 0) > 1:  # Return np-array if multidimensional
-            indexable = NumpyIndexingAdapter(np.asarray(self))
-            return indexable.oindex[indexer]
-
-        result = self.array[key]
-
-        return self._handle_result(result)
+        return self._index_get(indexer, "_oindex_get")
 
     def _vindex_get(
         self, indexer: VectorizedIndexer
     ) -> PandasIndexingAdapter | np.ndarray:
         _assert_not_chunked_indexer(indexer.tuple)
-        key = self._prepare_key(indexer.tuple)
-
-        if getattr(key, "ndim", 0) > 1:  # Return np-array if multidimensional
-            indexable = NumpyIndexingAdapter(np.asarray(self))
-            return indexable.vindex[indexer]
-
-        result = self.array[key]
-
-        return self._handle_result(result)
+        return self._index_get(indexer, "_vindex_get")
 
     def __getitem__(
         self, indexer: ExplicitIndexer
     ) -> PandasIndexingAdapter | np.ndarray:
-        key = self._prepare_key(indexer.tuple)
-
-        if getattr(key, "ndim", 0) > 1:  # Return np-array if multidimensional
-            indexable = NumpyIndexingAdapter(np.asarray(self))
-            return indexable[indexer]
-
-        result = self.array[key]
-
-        return self._handle_result(result)
+        return self._index_get(indexer, "__getitem__")
 
     def transpose(self, order) -> pd.Index:
         return self.array  # self.array should be always one-dimensional
@@ -1953,28 +1938,16 @@ def __array__(
         else:
             return super().__array__(dtype, copy=copy)
 
-    def _convert_scalar(self, item):
+    def _convert_scalar(self, item: Any):
         if isinstance(item, tuple) and self.level is not None:
             idx = tuple(self.array.names).index(self.level)
             item = item[idx]
         return super()._convert_scalar(item)
 
-    def _oindex_get(self, indexer: OuterIndexer) -> PandasIndexingAdapter | np.ndarray:
-        result = super()._oindex_get(indexer)
-        if isinstance(result, type(self)):
-            result.level = self.level
-        return result
-
-    def _vindex_get(
-        self, indexer: VectorizedIndexer
+    def _index_get(
+        self, indexer: ExplicitIndexer, func_name: str
     ) -> PandasIndexingAdapter | np.ndarray:
-        result = super()._vindex_get(indexer)
-        if isinstance(result, type(self)):
-            result.level = self.level
-        return result
-
-    def __getitem__(self, indexer: ExplicitIndexer):
-        result = super().__getitem__(indexer)
+        result = super()._index_get(indexer, func_name)
         if isinstance(result, type(self)):
             result.level = self.level
         return result